Toy cap gun having a parabolic gas expansion chamber



Nov. 12, 1968 J. v. MILLER ET AL TDY CAP GUN HAVING A PARABOLIC GASEXPANSION CHAMBER Filed May 24, 1967 wmw M i ,1 E A/ um? M wm wiwfl W50&5 1 a n WW Jew.

United States Patent 3,410,013 TOY CAP GUN HAVING A PARABOLIC GASEXPANSION CHAMBER Jack V. Miller, Sierra Madre, Ronald W. Froelich,Arcadia, Edward E. Headrick, La Canada, and George C. Strader, SanDimas, Calif., assignors to Wham-0 Mfg. Co., San Gabriel, Calif., acorporation of California Filed May 24, 1967, Ser. No. 640,873 13Claims. (Cl. 4254) ABSTRACT OF THE DISCLOSURE A toy cap gun having aperforated striking anvil, a hammer and a parabolic gas expansionchamber, the anvil forming a boundary of the chamber adjacent the focusof the chamber. Acoustic energy produced by detonatin a percussion capbetween the anvil and the hammer is communicated to the chamber and isthere controlled to closely resemble the sound of a gunshot and toproduce shock waves.

Background of the invention Field of the invention.--This inventionrelates to toy cap guns and, more particularly, to toy cap guns having aparabolic expansion chamber to which gases from the explosion of apercussion cap are introduced for focusing of the sound and shock wavesproduced by the explosion.

Description of the prior ort.Presently available toy cap guns are veryinefficient in the utilization of energy derived from the explosion of apercussion cap. Existing percussion cap guns are characterized by aserrated hammer which strikes against a flat anvil on which the cap issupported. The expanding gases produced by explosion of the cap arerequired to follow paths between the opposing surfaces of the anvil andthe hammer to escape and create an audible noise. In following thesepaths, the speed of the escaping gas is greatly reduced due to surfacedrag against the hammer and the anvil. As a result, the volume of soundproduced in existing percussion cap pistols is appreciably less thanthat theoretically produced by the cap.

A further characteristic of existing percussion cap pistols is that thesound waves generated by explosion of the cap are not directed to theareas where they can best simulate the sound of a gunshot. The soundwaves must propagate in a plane between the hammer and the anvil and,since the sides of the anvil are usually bound by guide rails to guidethe strip of caps, the bulk of the energy of detonation is eitherdirected upward or downward. Since the waves directed downward arealmost entirely absorbed in the gun mechanism, only the upwardlydirected sound waves can effectively be heard. As a result, the playvalue of a conventional existing toy percussion cap pistol is less thanoptium because the person at whom the pistol is aimed in play does notreadily hear the report of the caps explosion.

Moreover, the report produced by operation of an existing toy cap pistoldoes not accurately reproduce the sound of the gunshot it intended tosimulate because the sound frequency spectrum of an exploding percussioncap varies considerably from that of an explosion emanating from the gunbarrel of a pistol.

Summary of the invention A cap gun constructed according to thisinvention closely simulates the sound of an actual gunshot, preferablythat of a pistol shot. The gun includes an expansion chamber forcontrolling the gases produced in the explosion of a percussion cap anda perforated anvil upon which the cap is supported during its explosion,the anvil forming a boundary of the expansion chamber.

Sound waves created by striking a hammer against a percussion capsupported on the anvil are communicated to the chamber through theperforations in the anvil. The chamber is configured to direct theacoustic energy of the cap detonated in a desired direction with aminimum of energy loss in the gun structure. The configuration of theexpansion chamber preferably is such that its resonant frequency isclose to that of the predominant frequency of a gunshot. Accordingly,the sound produced by the explosion of a percussion cap in the presentgun closely simulates the sound of an actual gunshot.

The initial expansion of the gases produced in the detonation of apercussion cap occurs at supersonic velocities, thereby generating ashock wave. This shock wave is optimized in the expansion chamber of thepresent gun and is directed from the gun in the same direction as thedirection of audible sound propagation. This shock wave can be feltwithin a relatively large distance from the gun. The shock wave is feltas a harmless physical impact upon a person at whom the gun may beaimed, and if such person is standing reasonably close to the gun, hefeels the impact of the shock Wave before he hears the sound of the capdetonation. Accordingly, the play value of the present gun isappreciably enhanced over that of existing toy cap guns.

Generally speaking, the invention provides a percussion cap gun whichincludes a body. A perforated striking anvil is mounted on the body forreceiving a percussion cap. A hammer is mounted on the body for movementinto engagement with the anvil with a force sufficient to detonate apercussion cap supported on the anvil. The body adjacent the anvildefines a chamber for the expansion of gases produced in the detonationof a cap, the chamber having an opening to the exterior of the body at alocation spaced from the anvil. The anvil defines a portion of theboundary of the chamber. Thus, detonation gases are introduced into thechamber through the anvil, which gases expand in the chamber to producesound waves. The walls of the chamber are arranged to direct the soundwaves to the chamber opening. Also, the chamber walls are arranged sothat, as the sound wave fronts move toward the opening, they haveessentially only grazing incidence with the chamber walls.

Brief description of the drawings FIG. 1 is an outline in cross-sectionof a detonation gas expansion chamber in a gun constructed according tothis invention;

FIG. 2 is an elevation, partly in cross-section, of the gun; and

FIG. 3 is an elevation of another form of the gun.

Description of the preferred embodiments As shown in FIG. 1, apercussion cap gun 10 constructed according to this invention includes abody 11 defining a handle 12. The body defines an internal chamber 13having an open end 14 at the end of the chamber which corresponds to thedischarge end of an actual gun which gun 10 is intended to simulate. Gun10 is con- 3 structed in the style of a western six-shot revolver, andthus has a false barrel chamber 13 is defined within the portion of thebody which simulates the revolving cartridge holder of an actualrevolver.

In a manner similar to the construction of conventional percussion capguns, the interior of handle 12 is made hollow to receive a roll 16 ofpercussion caps, such caps normally being manufactured in the form of apair of strips of paper laminated together and having small quantitiesof impact detonating explosive disposed between the paper strips atregular intervals along the strips. Cap roll 16 preferably is looselysupported on a pin 17 within the gun handle. The strip of caps is ledfrom the roll past a striking anvil 18 mounted on the gun body adjacenta hammer member 19, the anvil being located between chamber 13 and thehammer member.

The hammer member is a part of a cap strip advancing and cap detonatingmechanism of the gun, which mechanism also includes a trigger 20. Theadvancing and detonating mechanism may be of conventional construction.A suitable cap strip advancing and cap detonating mechanism isillustrated in US. Patent 2,855,714. Regardless of the specific type ofmechanism used, hammer member 19 is mounted, preferably pivotally, onthe gun body for movement into engagement with the anvil with sufficientforce to detonate a cap supported on the anvil. Detonating motion of thehammer member toward the anvil is produced by operation of trigger 20.

As shown in FIG. 2, chamber 13 is elongated along a line 21 parallel tothe length of barrel 15. Anvil 18 is located at the end of the chamberopposite from the chamber open end and actually forms a portion of theboundary of the chamber. Preferably, the anvil is centered on line 21and is generally normal to the length of the chamber. Also, as shown,the anvil is provided with perforations 22 through it communicating thecap supporting surface of the anvil with the chamber. The hammer memberhas a hammer head 23 which is sized to cover all of the anvilperforations when it is in the position depicted. Therefore, when a capsupported on the anvil is detonated by forceful engagement of the hammerhead with it, the gases produced by the detonation follow the path ofleast resistance through the anvil perforations into the chamber.

The perforations in the anvil are as large and as many :as possibleconsistent with rigidity of the anvil itself. If the anvil is tooheavily perforated, it will yield undesirably under the impact of thehammer. If the yield of the anvil is too great, i.e., if the anvilabsorbs too large a fraction of the energy of the hammer, a capsupported on the anvil may not receive sufficient energy to producedetonation. Consistent with these criteria, the anvil perforations aremade as large as possible to produce the least possible resistance tothe passage of the detonation gases into the chamber.

Manifestly, the anvil has a finite thickness. Thus, perforations 22direct the detonation gases into the chamber along lines generallyparallel to line 21.

Obviously, the detonation of a percussion cap produces acoustic energyas the gases produced by the detonation compress the adjacent air duringtheir expansion. Because of the construction of the anvil and the hammerof gun 10, the detonation gases do not begin to expand appreciably untilthey enter chamber 13. As they enter the chamber and expand therein,they produce sound waves which travel along the chamber and out theopening. The walls 24 of chamber 13 between the anvil and opening 14 arearranged to focus these sound waves to propagation along lines parallelto line 21 with the minimum loss ofthe energy embodied in such soundwaves. Moreover, the chamber has dimensions which are selected so thatthe chamber has a resonant acoustic frequency which approximates thepredominant frequency in the acoustic energy spectrum of an actualgunshot, preferably an actual pistol shot. As a result, gun 10 operatesto simulate the sound of a true gunshot with a fidelity and loudnessheretofore unknown.

Chamber 13 preferably is symmetrical about line 21. Preferably, theconfiguration of the chamber is basically that of a truncatedparaboloid, a paraboloid being the surface formed as a parabola isrotated about its axis of symmetry. A paraboloid configuration ofchamber 13 is preferred because such a configuration results in amaximum angle of incidence between the chamber walls and the fronts ofsound waves moving along the chamber axis. Where the angle of incidenceis 90, as where a sound wave propagates in a direction parallel to areflective surface, a minimum amount of the energy in the acoustic Waveis transferred to the reflective surface. The configuration of chamber13 is such that the angle of incidence at any point along the length ofthe chamber with a sound wave moving along the chamber axis is as highas possible. Preferably the angle of incidence, as described above,between sound waves moving along line 21 and the walls of the chamber isbetween about and about Thus, sound waves originating at the anvil makeonly grazing reflective contact with the chamber walls, and a 'minimumof acoustic energy in the waves is lost in the chamber. As a result, thesound heard by a person standing in front of gun 10 is as loud aspossible, and is considerably louder than the sound heard as a result ofthe operation of an existing percussion cap gun.

It has been found that an effective parabolic detonation gas expansionchamber for gun 10 is a chamber which has a maximum diameter ofapproximately 1.25 inches adjacent chamber opening 14, a minimumdiameter of about 0.375 inch adjacent anvil 18, and a length of about2.875 inches. Such a chamber configuration is illustrated in FIG. 1.

As shown in FIG. 1, it is preferred that the paraboloid defining theconfiguration of chamber 13 have its focal point 30 located outside thechamber adjacent the side of the anvil opening toward the hammer member;the paraboloid is thus truncated by the anvil. More specifically, it ispreferred that the focal point of the chamber paraboloid be in the planedefined by the cap supporting surface of the anvil. Since the focalpoint of the paraboloid is outside chamber 13, the gases and sound wavesentering the chamber through the anvil are travelling in the desireddirection. Thus, the chamber configuration functions to maintain thisdirection and to propagate the sound Waves into a flat plane at the openend of the chamber. The chamber configuration described aboveaccomplishes these purposes effectively.

The use of long, narrow chamber configurations should be avoided, asshould the use of short, wide configurations. Long, narrowconfigurations produce excessive losses of acoustical energy due ot thesame effects which cause pressure losses in fluids flowing throughpipes. Short, wide paraboloids do not produce the desired sounddirectionality; moreover, such paraboloids do not permit grazingincidence acoustical reflection, and therefore a significant portion ofacoustic energy is absorbed by the reflector.

It was mentioned above that chamber 13 is a tuned chamber. The length ofchamber 13 is selected relative to its diameter so that the chamber hasa resonant acoustical frequency in the range of from 800 to 1000 cyclesper second, and preferably of about 900 cycles per second. The acousticspectrum of an actual pistol shot has a peak at about 900 cycles persecond, whereas the predominant frequency in the audible spectrum of thesound produced by detonation of a toy percussion cap is about 2000cycles per second. Thus, a gun according to this invention preferablyhas a chamber about 3 inches long, and the ratio of chamber length tochamber diameter preferably is about 2.3:1. Such a gun realisticallysimulates both the loudness and the tone of an actual pistol shot,notwithstanding that the sound produced by a percussion cap per se has amuch different tone.

The initial expansion of the gases produced by detonation of theexplosive charge in a. percussion cap occurs at velocities which areseveral times greater than the speed of sound in air. Because hammerhead 23 completely covers the truncated end of chamber 13 over anvil 18,the gases produced upon detonation of a percussion cap supported on theanvil are forced to enter the chamber. The initial expansion of thesegases in the chamber produces a shock wave which travels down thechamber and out open end 14. This shock wave can be felt by a personstanding within about thirty feet of the gun and in front of the gun. Ifthe person is standing within about feet of the gun, he feels the shockwave before he hears the report of the cap detonation. If the person isstanding in the range of from about ten feet to about twenty feet of thegun, he feels the shock wave at about the same time that he hears thereport of the detonation.

It has been found that where the parabolic curvature of chamber 13extends entirely to the open end of the chamber, i.e., where thediameter of opening 14 is the maximum diameter of the chamber, theaccuracy of shooting the shock wave at an intended target is related tothe accuracy with which a percussion cap is centered on the anvil. Inorder to minimize the effect of erratic placement of a cap on the anvil,such positioning variations being common with existing repeating-actionca strip advancing mechanisms, chamber 13 is provided adjacent its openend with a shock wave focusing nozzle 31. Preferably, as shown in FIGS.1 and 2, the nozzle is of volute configuration and is defined by asurface 32 which is essentially normal to the chamber axis at themaximum diameter of the chamber and curves into parallelism with thechamber axis at the chamber open end. Preferably the nozzle is shaped toreduce the 1.25 inch maximum diameter of the chamber described above toabout 1.0 inch at open end 14.

Without the nozzle described above, it was found that the shock wavewould vary over an area one foot in radius on a target located ten feetfrom the gun. With a gun equipped with the shock wave focusing nozzledescribed above, however, the shock wave was found to be concentrated inan area 3 inches in diameter twenty feet from the gun, and that theshock Wave consistently hit a target twenty feet from the gun within afew inches of the aiming point. At this range, the force of the shockwave is sufficient to move or tip over light targets made of plastic orpaper. The provision of the shock wave focusing nozzle at the mouth ofchamber 13 does not detract from the loudness of the sound produced bythe gun.

Barrel 15 of gun 10, in cooperation with the remaining structure of thegun, makes it impossible for a child using gun 10 to place the gun incontact with his head so as to seal the open end of chamber 13 againsthis ear. Thus, it is not possible for a child to use the gun in a mannerwhich may produce permanent or semipermanent damage to his or anothershearing. Gun 35, shown in FIG. 3, has a futuristic appearance, but likegun 10 is shaped, as at 36, adjacent the opening of chamber 13 to theexterior of the gun in a manner which prevents a child from sealing thechamber opening against this ear. As a result, guns 10 and 35 are safeboth as to their users and to persons at whom the gun may be pointed.

As shown in FIG. 3, where nozzle 31 is located intermediate the passagebetween the anvil and the exterior of the gun, the diameter of thepassage between the nozzle and the exterior of the gun is enlarged tothe greatest extent possible to minimize loss of acoustical energy tothe greatest extent possible. Preferably the transition from the nozzleto the enlarged diameter of the passage is a sharp step as shown in FIG.3.

The guns described above, as already noted, have several features notfound in existing percussion cap guns. The sound produced by thedetonation is directionalized to be loudest in the direction in whichthe gun is pointed. Also, the acoustic energy produced by the detonationof the cap is handled efliciently in the gun to increase the loudness ofthe gun report, the tone of which is regulated so that the audiblereport of the gun closely simulates the sound of an actual gunshot.Moreover, the gun is configured so that detonation of a percussion capproduces a directionalized shock wave. All these features result in theprovision of a gun which has a play value significantly higher thanexisting percussion cap guns.

It should be realized that the features and improvements provided bythis invention are not restricted to repeating-action toy pistols. Thesefeatures may be incorporated into a single shot toy pistol or rifle.Where the invention is used in a toy rifle, it is within the scope ofthe invention that the proportions of the detonation gas expansionchamber be modified from those given above by way of example so as tohave a resonant frequency according with the predominant frequency ofthe sound of an actual rifle shot.

What is claimed is:

1.-A percussion cap gun comprising a body, a perforated striking anvilmounted on the body for receiving a percussion cap, a hammer mounted onthe body for movement thereof into engagement with the anvilsufficiently forcefully to detonate a percussion cap supported on theanvil, and a chamber defined by the body adjacent the anvil and havingan open end spaced from the anvil, the anvil forming a portion of theboundary of the chamber so that gases from the detonation of apercussion cap supported on the anvil are introduced into the chamberfor expansion thereof in the chamber to produce sound waves, the chamberbeing configured concave from the anvil toward the open end to directthe sound waves from the anvil toward the chamber open end, the chamberwalls being arranged so that the fronts of sound waves moving toward theopen end have essentially only grazing incidence upon the walls.

2. A gun according to claim 1 wherein the chamber has a truncatedparaboloid configuration symmetrical about a line extending along thelength of the chamber between the anvil and the center of the chamberopen end.

3. A gun according to claim 2 wherein the length of the paraboloid isabout 2.3 times the maximum diameter of the chamber.

4. A gun according to claim 2 wherein the paraboloid is truncated by theanvil.

5. A gun according to claim 4 wherein the anvil is disposed in a planesubstantially normal to the paraboloid axis.

6. A gun according to claim 4 wherein the paraboloid has its focuslocated externally of the chamber.

7. A gun according to claim 6 wherein said focus is locatedsubstantially coincident with the surface of the anvil with which thehammer is engageable.

8. A gun according to claim 1 wherein the chamber has a resonantacoustical frequency in the range of from about 800 to about 1000 cyclesper second.

9. A gun according to claim 8 wherein the said resonant frequency isabout 900 cycles per second.

10. A gun according to claim 1 wherein the expansion of detonation gasesin the chamber produces a shock wave which moves along the chambertoward the chamber open end, and including a nozzle defined by the bodyat the chamber open end for focusing said shock waves, the nozzle beingconfigured so that the chamber open end has a diameter less than themaximum diameter of the chamber.

11. A gun according to claim 10 wherein the nozzle is of voluteconfiguration and includes a surface extending circumferentially of thechamber open end and curving at the chamber maximum diameter fromsubstantially normal to a line between the anvil and the chamber openend about which the chamber is symmetrical to substantially parallel tosaid line at the chamber open end.

12. A gun according to claim 11 wherein the diameter of the chamber atsaid open end is approximately fourfifths of the maximum diameter of thechamber, which maximum diameter is located immediately adjacent thevolute toward the anvil.

13. A gun according to claim 12 wherein the chamber has a truncatedparaboloid configuration, the chamber being truncated by the anvil, theanvil being disposed substantially normal to said line, the chamberhaving a minimum diameter of about 0.375 inch adjacent the anvil and amaximum diameter of about 1.25 inches, and a length between saiddiameters of about 2.875 inches.

References Cited UNITED STATES PATENTS 738,585 9/1903 Wenzel 42572,983,064 5/1961 Hirsch et al. 4258 BENJAMIN A. BORCI-IELT, PrimaryExaminer.

